High fluoride intake may boost risk of forearm fracture

A study in Epidemiology suggests that high cumulative intake of fluoride or long term exposure to fluoride through water fluoridation may boost risk of forearm fracture in women.

Some other studies have suggested that high intake of fluoride may increase risk of hip fracture.

Fluoridation is a process by which fluoride is added to tap water to help dental caries. But there is some concern about its toxicity as it can increase risk of fluorosis if the exposure is excessive.

For the current study, Feskanich D and colleagues of Brigham and Women's Hospital and Harvard Medical School in Boston, Mass collected toenail clippings from 62,641 women enrolled in the Nurses' Health Study who were at baseline free of cancer, heart disease, stroke and previous hip or forearm fracture.

During the follow-up, the researchers identified 53 proximal femur and 188 distal forearm fractures through biennial questionnaires and compared the cases with controls who did not have fractures to see if fluoride intake would have anything to do with the risk of fractures.

Women in the highest quartile (greater than 5.50 ppm) of toenail fluoride, which is indicative of long-term accumulation of this mineral in an individual, were 20 percent less likely to have hip fracture, compared with those in the lowest quartile (less than 2.0 ppm) of toenail fluoride.

The association was found after adjustment for menopausal status, postmenopausal hormone use, caffeine intake and alcohol drinking.

However, the risk for forearm fracture was 60 percent higher in those with the highest level of fluoride (5.50 ppm or higher), compared with those who had the lowest level of toenail fluoride.

The association was not affected by adjustment for body mass index, smoking status, intake of calcium and vitamin D.

In the U.S., the government recommends fluoride be added to tap water at a level between 0.7 ppm and 1.2 ppm.